RQC Seminar

103rd RQC Seminar

• Speaker

  Dr. Anton Frisk Kockum
  ( Department of Microtechnology and Nanoscience, Chalmers University of Technology, Sweden )

• Date

  13:30-14:30, December 28, 2023 (Thursday)

• Venue

  Hybrid(ZOOM・ Wako Main Research 3F 345-347 Seminar Room C01）

• Title

  Measuring the quantum state of a photoelectron

• Inquiries

  rqc_info[at]ml.riken.jp

Abstract
A photoelectron, emitted due to the absorption of light quanta as described by the photoelectric effect, is often characterized experimentally by a classical quantity, its momentum. However, since the photoelectron is a quantum object, its rigorous characterization requires the reconstruction of the complete quantum state, the photoelectron's density matrix. Here [1], we use quantum state tomography to fully characterize photoelectrons emitted from helium and argon atoms upon absorption of ultrashort, extreme ultraviolet light pulses. The experiments were performed in the group of Anne L’Huillier (2023 Nobel laureate in physics) and David Busto at Lund University, with theory support from my group at Chalmers University on the reconstruction of the quantum state from sparse data. While in helium we measure a pure photoelectronic state, in argon, spin-orbit interaction induces entanglement between the ion and the photoelectron, leading to a reduced purity of the photoelectron state. Our work shows how state tomography gives new insights into the fundamental quantum aspects of light-induced electronic processes in matter, bridging the fields of photoelectron spectroscopy and quantum information, and offering new spectroscopic possibilities for quantum technology.

[1] Laurell et al., arXiv:2309.13945